travis.sadecki@LIGO.ORG - posted 15:18, Friday 27 February 2026 - last comment - 16:01, Monday 09 March 2026(89308)
HAM1 +Y door installed
The HAM1 +Y door was installed today. Installation went smoothly and the O-ring cooperated by staying in place today. I will note that torquing the door bolts is becoming more of an issue due to wrench access being increasingly limited near the 5-way cross/feedthru areas now that all the in-air cables have been attached.
The HAM1/HAM2 annulus system is being pumped by 2 turbos/aux carts on the -Y side of the chambers. The mysterious ~order-of-magnitude pressure readout difference at the two carts on the shared annulus system is again present, as was noted the last time this annulus system was pumped down. Not an issue per se, just some vacuum phenomena that leaves us scratching our heads.
Vent Recovery Update
Annulus ion pumps for HAM1 and HAM2 continue to pumpdown, we closed the isolation valves for both of them, but the ion pumps were not able to maintain pressure. On 3/4/26 valves were opened again to continue using the aux carts, and yesterday (3/5/2026) we isolated the aux cart for HAM2 only, all of that can be seen on the attached plot.
Aux carts will be left pumping and annulus systems are going to be evaluated next Monday.
I isolated the HAM1 aux cart (HAM2 was isolated on Friday) from the annulus this morning. The IP current only rose to ~4.7mA before turning around showing it could hold the annulus pressure.
HAM1/2 annulus aux carts were shut down and decoupled this afternoon. The SS500 cart remains at HAM1 and will continue to pump until the pressure is low enough to valve in the HAM1 ion pump.